Adjustable condenser



Aug. 9, 1932. w. DUBILIER ADJUSTABLE CONDENSER Filed Feb. 1. 192e 2 sheets-Sheet 1 l BY ATTORNEY d WILLIAM DUZBI'LIER, CIIE NEW v'ROCHELLE,

Patented Aug. 9, 1932 UNI TAE .1S T A TE S Asis ,E

.rr-ica NEW YOEK, ASSGNORn 'TO DVUB'ILIEEB CON- DENSER CORPORATION, 0F 'NEW YORK, N. Y., A CRPORTIOIT TOF DELAWARE ADJUSTABLE CONDENSER Application led February adjusted to vary the electrostatic capacity.

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An object of my invention is to provide a simple and practicail condenser that can be enclosed in 'a suitable casing, the interior of. which ycan be'sealed `up and which can even be embedded in insulating material solid at ordinary temperatures, and yet permit the condenser to be readily .adjusted from the exterior of .the casing 'to give the change ot capacity desired. Y

Other obfects .and advantages oi this 'invention will beset forth in the following description takenV with the accompanying. drawings in which pone or more embodiments of my invention are illustrated. This dis-f closure, however, is explanatory only and l may vary 'the construction actually set forth to the full extent indicated by the broad and general meanings 0f the terms in which the appended claims are expressed.

Onthe drawings, f Figure 1 is a view in longitudinal section, showing an adjustable condenser according to my invention; j j Figure 2 is a'transverse section on the line 2-2 of Figure 1;

' Figure 3 is a `view showing a modiiication of one of the fparts of the condenser;

Figure 4 is a plan View of one of Vthe adjustable parts of the condenser appearing in Figures l and 2;

.Figure '5 shows a perspective View of the casing of a radio receiving set with which my condenser can be utilized; 4 Figure 6 is a view similar to Figure 1, showing another form of inyicondenser with the casing .housing the condenser embedded in 4insulation such as wax;

Figure 7 is a section on the line 7,-7 of Figure 6;

Figure 8 yis la vliew similar to Figure 6 showing another condenser according to my inven-V tion; and Figure 9 shows in axial section a further modification.

'0n the drawings,

identify the same :parts throughout;

Referring first to Figures '1, 2 and 4, I

Athe same numerals 1, 1926. .Serial No. 85,361.

show at 1 a casing with a closed `bottom and Open top, `provided with a lid or closure '2. This lid 2 is sealed in place as by soldering the lid o-n the casing 1, and in the bottom ot the casing is a central opening 3 through which M projects a screw 4 `havin-g an enlarged head 5 in the form of a disc which rests upon the bottom of the casing 1, is'insu'lated therefrom, and co-operates with a disc 16 which can be maderout of' a plate of metal, stamped oio otherwise shaped to be convex on one face, this convex :tace being vpresentedto the disc or plate 5. Both oit' the elements and 6 must, of course, 'be of conductive material and the capacity ot the condenser is varied g5 by Vpressing the periphery of the element 6 towards the disc 5, so as to bring afl-arger Yor smaller portion of the surface of the element 6 closer to the surta-cecil the'disc 5, `andthus vary the capacity of the condenser at will.` 70 The `element 6 is controlled lby a screw l7 which projects into the casing --1 and carries a head 8 engaging the vperiphery of the element 6. This screwthreadedstem T'ismounted in a threaded opening ina boss 9 `carried 75 centrally by the closure 2, and the outer end of the stein 7 has a hert in it to enablev it to be engaged by a screw, s0 'thatthe 'stem' 7 can be turned tocompress or release the `element-6. -The exterior of the boss 9 is threaded 50 at I11 so that a cap 12 can be screwed o-n this boss to cover the exterior end of the stem 7.

In practice, I may mount this condenser von the interior of the casing 13 of al radio -receiving set, this casing having an opening g5 14through which the cap 12 can proj-ect. rThe casing with the condenser inside of same may be sealed inside of the casing 13, but the condenser can be adjusted at any time merely by removing the cap and yapplying a tool "to no the llzerf 10, so as to turn the stem 7.

` On top of the disc 5 is a 'sheet 'of insu-lation such as mica 15, and a similar sheet of insulation lies between this disc, and the bottom of thecasin-g ,1, so that the disc is not in con- 9'5 tact with'l the casing. The opening 3 is, of course, ofrgreater diameterthanthe screw 4. Outside of vthe casing the exterior v:tace of the bottom is in contact with a sheetof mica 16, against which is a sheet of metal such as tin- 100 foil 17, these two sheets being perforated to give passage to the screw 4, and at 18 is a block of brass or the like, forming a washer to be slipped over the outer end of the screw 4 and be held in place by a nut 19. The element 6 is of course made of thin metal, so as to be resilient to permitcompression, and I preferably provide it with a series of cuts 20 extending from the periphery towards the centerto make this element more flexible. If desired, I may substitute for the element 6, an element which is in the form of a flat f strip of metal wound in the form of a conical esY spring which may be wound edgewise as illustrated by spring 21 in Figs. 6 and 7, or flatwise as illustrated by spring 21a yin Fig. 3. This spring may rest upon the top disc of Y insulation 15, and the head 8 may be omitted so as to permit the 'inner end of the stem 7 to engage the center of the spring 21 or 21a to compress and release it and thus by causing a greater or smaller portion of the turns of this spring to be located closer to or farther from the element 5, a change'in capacity can be given.

TheY housing or cabinet 13 of the radio set may have openings 22 in the top containing sockets in which vacuum tubes can be mounted. Sometimes it is desirable to embed the parts of a receiving set in wax which is put in place by melting and pouring it in. In such instances, the parts of the set are first mounted in the cabinet13, and after the wax is poured in, the top of the casing is aflixed in place. The cabinet may be filled with wax up to the top, which bears the openings 22 and 14. Then the casing 1 of the condenser will be completely embedded up to the lid or closure 2 as indicated more fully at W in Figures 6 and 8.

In Figure 6, I show a condenser with a spiral spring 21 in place of the convex plate 6 and this spring is compressed by a threaded screvs7 or stem 7 which engages the middle of the spring and has no head 8 at its inner end. The disc or element 5 as before, has sheets of insulation 15 on both the top and bottom of same and between the lower sheet of insulation 15 andthe bottom of the casing, is a disc of tin-foil 17. Against the outside face of the bottom of the casing is a sheet of insulation such as mica and a sheet of tinfoil 17 as before held in place by a washer 18 which is secured on the outer end of the screw 4 by two units 19. These two units 19 grip between them a conductor fastening lug 26, having an opening in one end to receive the end of the conductor.

To mount the casing with this form of condenser in place, I employ a. threaded bushing 24, the lower end of which is of reduced thickness, to go through an aperture in the closure 2. The end which projects through this closure is expanded as indicated at 25, to secure the bushing in position. The screw 7 goes through a threaded bore in this bushing, and another conductor fastening device 26 engages the top of the casing and is held against the under side of the top 32 of the cabinet of a radio receiving set, such as shown in Figure 5. A washer 27 surrounds the bushing 24 of the upper face of the top 32, and 28 is a lock nut screwed upon the threaded exterior of the bushing 24 to make the bushing fast with the top 32 and support the casing 1 with the condenser therein rom this top 32. On top of the nut 28 is a rubber washer 29 and on this rubber washer 29 is a metallic washer 30, and at 31, I show a. cap similar to the cap 12, to screw upon the end of the bushing 24 and cover the external end of the stem 7.

This form of condenser as will be seen is mounted upon the lower or inner face of the top 32 of the cabinet of the radio receiving set, and is secured by means of the bushing 24, the nut 28, and associated parts. lVhen the housing of the set is filled with wax indicated at W, the casing 1 may be completely embedded, and yet by taking olf the'cap 31, and turning the stem 7, the condenser can be adjusted as before. Of course, the bushing 24 must be of conductive material. so that while the element 5 is connected to one terminal of the circuit through the lower lug 26, the element 21 in the casing can be connected to the opposite side of the circuit through the stem 7, the bushing 24 and upper lug 26.

In F igure 6, the top 32 is shown as of insulation. Figure 8 shows a similar top 33 of metal. In this case, the condenser is made the same before only I employ a bearing 34 of insulation threaded inside and outside, and held in place by lock nuts 35 engaging the upper and lower faces of the top 33. Themetallic bushing 24 is simply screwed into this bushing 34 and this bushing 34 holds the upper lug 26 against the top 2 of the casing 1. The upper end of this bushing 34 which projects through the top .is engaged Vby the cap 31 which covers the exterior end of the stem 7 The condenser of Figure 8 can also be embedded in wax after being connected in circuit and be adjusted as before by removing the cap 31 and turning the screw 7.

The mica washer 15 in the bottom of the casing 1 serves to center the element 5 on the screw 4 by means of the opening through the middle of this washer. Y

It will be seen that the capacity of the condenser is due not only to the disc 5 and theelement 6, or the element 21, but also to the metal casing 1 in contactwith the tin-foil 17 on the bottom. this tin-foil and casing thus cooperating with the element engaged by the stem 7;

' and to the tin-foil against the outer insulation washer 15 whichy is in electrical connection with the disc 4 and thus cooperates with the disc 5. In Figure 1, no tin-foil is placed on the bottom of the casing 1, but the casing `itself cooperates with the movable element controlled by the threaded stem. The condenser thus includes a plurality of Xed elements, but only one element is movable and the adjustment is secured thereby.

In Figure 9, the casing 1 is in the form of an inverted cup having an opening in the bottom in which is riveted a bushing 24, which is threaded outside, and has a threaded bore to receive the threaded stem 7 to engage the element 21. The inverted mouth of the cup is closed by an insulating cover 36 which lits against a shoulder in the cup, and the rim of the cup is flanged over to hold this insulating closure 36 in place. On this closure, rests the metal dise 5 which has sheets or washers of mica, as before, on its upper and lower faces, this disc being out of Contact with the casing 1. From the disc 5 a threaded stem 4c extends through the closure 36 carrying a washer 18, and a binding nut 19. Terminals 26 as before can be held in Contact with the nut 19 and the inverted bottom of the casing 1, and nuts 35 on the bushing 24, can be used to support this construction on the top of a casing or panel 32 as in Figure 6.

Having described my invention, what I believe to be new and desire to secure and protect by Letters Patent of the United States is 1. A radio set with insulation, and a condenser embedded in said insulation and adjustable from without the same.

2. A radio set comprising a cabinet containing parts embedded in insulation, and a condenser also embedded in said insulation and adjustable from the exterior of the cabinet.

3. Radio apparatus having parts thereof, including a variable condenser, embedded in insulation, and means operable from a point without said insulation for adjusting said condenser.

4. Radio apparatus having elements thereof embedded in insulation, at least one of said elements being adjustable, and means operable from a point without said insulation for adjusting said adjustable element.

In testimony whereof I aHX my signature.

WILLIAM DUBILIER. 

